Universe of Origin: Nightmare
Having succumbed to vampirism while hunting Dracula, Nightmare Batman’s unnatural speed and strength make him one of the most formidable and terrifying assassins in the Multiverse.
Initially, Bruce Wayne controlled the hunger, augmenting his skills with his newly gained vampiric abilities to fight his war on crime. In time, the hunger became too great and he brutally murdered the Joker, gorging on his blood. His control snapped, what remained was a wild killing machine, unpredictable but efficient.